The Algebra Teacher\'s Guide to Reteaching Essential Concepts and Skills

Name Date

WORKSHEET 3.2: SOLVING EQUATIONS BY ADDING

OR SUBTRACTING

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Follow the steps below to solve an equation by adding or subtracting:

1. Isolate the variable on one side of the equation by adding the same number to both
   sides or subtracting the same number from both sides.


2. Find the value of the variable.

EXAMPLES

Solve each equation.

x− 9 =− 15 To isolatex,add9toeachside.

+ 9 + 9

x=− 6

x−(−3)= 14 To isolatex, rewrite the problem asx+ 3 = 14 , then subtract 3 from

x+ 3 = 14 each side.

− 3 − 3

x= 11

DIRECTIONS: Write the number you would add to or subtract from both sides of the

equation. Then solve the equation.

1. x−(−6)= 15 2. x+(−7)= 20


2. 4 −(−y)= 13 4. − 4 =z+(−32)


3. − 3 +x=− 8 6. n− 6 =− 9


4. − 4 =s+(−4) 8.

2

5

=n−

3

5

CHALLENGE:Sal solved the equationx− 3 + 2 =−10 by adding 3 to both

sides, then subtracting 2 from both sides. He got the correct answer,

x=−9. Mike solved the same equation by adding 1 to both sides. He got

the same answer as Sal. What did he do? And was his method correct?

91

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2011 by Judith A. Muschla, Gary Robert Muschla, and Erin Muschla. All rights reserved.